The present invention relates generally to a ribbon-like plate heat pipe and more particularly, to a ribbon-like plate heat pipe having a looped serpentine capillary tunnel container formed therein.
Various plate heat pipes having a capillary tube interposed between metallic plates have been developed for purposes of heat diffusion and transport. Such plate heat pipes have an extremely decreased thickness and weight due to application of, e.g. U.S. Pat. No. 4,921,041 to Akachi, and U.S. Pat. No. 5,219,020 to Akachi. However, with a quick progress of a reduction in size and weight of semiconductor devices as exothermic elements, there is an increasing demand for a further reduction in thickness and weight of the plate heat pipes.
In response to such demand, a tunnel-plate type heat pipe is proposed as disclosed in U.S. patent application Ser. No. 08/352,217 filed Dec. 2, 1994. This tunnel-plate type heat pipe comprises a first metallic plate having one side formed with a groove which forms a continuous channel therein, and has a predetermined number of turnings and a predetermined number of portions arranged in parallel with each other, and a second metallic plate disposed on one side of the first plate wherein the second plate closes the channel such that the groove of the first plate serves as a tunnel to be charged with a predetermined amount of working fluid. With this structure, the inner diameter of the tunnel can be 0.3 mm, resulting in a reduced thickness of the plate heat pipe up to 0.5 mm or less.
When forming the tunnel-plate type heat pipe, the metallic plates are joined according to a hard solder joining method and a diffusion joining method, which need not only a large-sized vacuum furnace, but a furnace face machining jig or press working machine for face joining in the furnace. This results in a restricted maximum size and area of the heat pipe, which corresponds to approximately 1 m.times.1 m for a plate-like heat pipe, and 100 mm.times.2 m for a ribbon-like heat pipe. Moreover, the size of an NC milling machine for machining a groove in one side of the metallic plate, various devices for photo-etching of a groove pattern, etc. operates to prevent an increase in size and area of the heat pipe.
It is, therefore, an object of the present invention to provide a ribbon-like plate heat pipe which has a largely increased size and area.